Conventionally, as a device which controls emission of exhaust of an engine by aftertreatment, there is known a selective catalytic reduction (SCR: Selective Catalytic Reduction) type exhaust emission control device which reduces nitrogen oxide (NOx) in the exhaust by using ammonia.
In this exhaust emission control device, a reduction catalyst for nitrogen oxide (NOx) is disposed in an exhaust passage, a urea aqueous solution supply device is disposed upstream of this nitrogen oxide (NOx) reduction catalyst, and an oxidation catalyst for defecating ammonia is disposed downstream thereof. Ammonia is generated by hydrolysis of urea added to the exhaust by the urea aqueous solution supply device, and this ammonia is supplied to the nitrogen oxide (NOx) reduction catalyst as a reducing agent. On the other hand, ammonia (ammonia slip) which has passed through the nitrogen oxide (NOx) reduction catalyst, without contributing to reduction of the nitrogen oxide (NOx), is oxidized and defecated with an ammonia defecate catalyser before emitted into the atmosphere.
In the selective catalytic reduction (SCR) type exhaust emission control device, in a container for a designated fluid, there has been needed a device that is referred to as an identification sensor which is a separate device from a pump, in addition to the pump for suction. A fluid to be used has been managed by utilizing such a device (see, for example, Patent Documents 1 and 2).